1. Field of the Invention
The present invention relates to a transfer method of an adhesive film, and especially relates to a method for adhering an adhesive film (adhesive tape) for mounting in a width of a several millimeters, represented by an anisotropic conductive film (ACF) or the like, to an adherend.
2. Description of the Related Art
Anisotropic conductive films (ACF) have conventionally been used as means for connecting electronic parts and a circuit board, and the like. The anisotropic conductive film is used for adhering and electrically connecting various terminals to each other, including the case for connecting a flexible print circuit or terminals of IC chip to an indium tin oxide (ITO) electrode formed on a glass substrate of a LCD panel.
The adhesion (transfer) of an adhesive film, represented by this anisotropic conductive film (ACF) or the like, to an adherend has been carried out in the manner described in the following (1) to (4).
(1) At first, as shown in FIG. 2A, a knife 17 is inserted into an adhesive film consisted of a base film (release layer) 11 and an ACF layer (adhesive layer) 12 from the side of the ACF layer 12, only the ACF layer 12 is cut 12d at the predetermined length and the predetermined width (approximately 100 μm) to thereby carry out a half cut (for example, see Japanese Application Laid-Open (JP-A) No. 2006-93518). At the time of this half cut, the attention should be taken not to cut the base film.(2) Next, as shown in FIGS. 2B and 2C, the adhesive film is pressurized with a heating head 14 of a preattachment device from the side of the base film 11, and the ACF film 12 is brought into contact with a panel (adherend) 15 while being heated, to thereby temporarily adhere to a connection section of the panel 15, which is in the size of several millimeters to several centimeters.(3) Thereafter, the base film 11 is peeled (as the cut 12d having the predetermined length has been formed in the ACF layer 12, only the ACF layer 12 having the predetermined length, which is in contact with the panel 15, is remained on the panel 15).(4) The ACF layer is connected with IC or wiring, and then is pressure bonded, completely.
At the time when the knife is inserted into the ACF layer for the half cut described in (1), contaminants attached to the knife are mixed in the ACF layer, lowering the quality of the final product. Moreover, in the case of the half cut, there is a problem in the cost, as the maintenance is necessary for the knife to be inserted into the ACF layer, such as the regular replacement of the knife. Furthermore, failures in the half cut (insufficient cut and the like) are occurred unless the conditions for the half cut are sufficiently controlled (managed), the cutting of the ACF layer becomes insufficient (cutting failure of the ACF layer), which causes bonding failures 18 (FIGS. 2D to 2F). In order to prevent the bonding failures, a cut-out system, in which two knives 17 are inserted from the side of the ACF layer 12 (half cut in two places) and the cut-out whose width is larger than that in the half cut of (1) is formed, may be carried out (for example, see JP-A No. 2007-30085) as shown in FIGS. 3A and 3B. However, in this cut-out system, the portions of the ACF layer where are cut out 12e are wasted, and the production cost becomes high. In addition, as well as the half cut of (1), this system is necessary to sufficiently control (manage) the conditions for the half cut.
Moreover, as an adhesive film (adhesive tape), ones in which a softening point of an adhesive is specified have been used (for example, see JP-A No. 2007-154119).